"Wikimedia Developer Support" is just a name, don't take it too literal. What matters is that the questions are related to software development, no matter how basic or slightly related they might look like. In case of doubt, post your question anyway.

Discourse has a collection of features to help users follow the content that is interesting to them. Web and email notifications adapt to regular actions of the users (reading, replying, being mentioned, watching, muting...). For those willing to fine tune their setup to the extreme, Discourse offers many possibilities. Do you want to be notified only when someone mentions you? Do you want to receive an email for every action happening everywhere? Something in between?

Discourse offers five levels for tracking topics, tags, and categories. Reading a topic entirely or during a certain time will set it to a higher level, and of course replying in a topic too. Users can refine these actions in their Notification preferences. These levels can be set manually through an icon at the right of topic, tag and category pages. The default options depend on the configuration of the site, and they can be changed via user preferences. From less to more:

Muted: The user will not be notified about changes, and the topic(s) will not appear in their "Latest".

Normal: The user will be notified when someone mentions them or replies to their post/comment.

Watching first post (in tags and categories): Normal + the user will be notified about new topics created.

Tracking: Normal + in tags and categories the user will track all topics + a count of new replies will be shown in lists.

Watching: Tracking + the user will receive a notification for every comment.

Users will get email or web notifications depending on the defaults of the system and their user preferences. In addition to the notifications for new topics and replies mentioned above, they can receive other notifications, configurable:

Notifications when someone likes their posts or comments.

A periodical digest featuring the most relevant topics or activity, which will be sent only when the user is not active in the site.

A "mailing list mode" can be set in user preferences, which will generate emails for every action respecting muted topics, tags, and categories.

Missing a feature that others seem to have (aka user trust levels)[edit]

Discourse offers more features to users as they hit milestones using the site. This mechanism called user trust levels helps preventing spam as well as overwhelming new users with features that they might not need.

These are the default user trust levels and the basic features they can use: